EFFECTS OF PH AND GLUCOSE-CONCENTRATION ON THE PRODUCTION OF RIFAMYCIN OXIDASE BY CURVULARIA-LUNATA IN A BATCH REACTOR

Using a strain of Curvularia lunata, the effects of pH and glucose concentration in the cultivation medium on the cell growth and enzyme productivity have been investigated in a batch reactor. An initial pH 6.5 and a control pH 7 during cultivation yielded the best enzyme productivity. It was observed that enzyme production was not repressed by high glucose concentration up to 30 g l-1. Precise pH control was necessary to maintain the enzyme production at a desired level when a high sugar concentration was used. The maximum specific growth rate was 0.25 h-1 when the pH was maintained at 7, while it was only 0.20 h-1 without pH control or when the initial pH of the cultivation medium was adjusted to 6.5. Antifoam had no significant effect on cell growth and enzyme activity up to a concentration of 0.5% (v/v), but above this value the cell growth as well as enzyme activity decreased. C lunata forms large pellets rather than mycelia when a high sugar concentration was used and typical disadvantages of submerged culture cultivation of fungus appeared.